I'd have a look at early 90's GM DIS ignitions ( they came in 4 and 6 cyl , not sure about an 8 but you could use 2 of the 4 systems ) . These only need a crank signal and usually have a limp home spark advance curve built in.

Early 90's Ford Ranger 2.3 / 2.5 with dual spark had a similar system from what I recall.